Thymic Physiology and Biochemistry
Review articleOpen access
1987/01/01 Full-length article DOI: 10.1016/S0065-2423(08)60324-8
Publisher SummaryThis chapter discusses the anatomy and physiology of the thymus gland. It focuses on variety of polypeptides that are produced by thymic epithelial cells and that are well-characterized biochemically. The various primary and secondary immunodeficiency disorders that are associated with abnormalities of the endocrine thymus are also discussed. The thymus gland is required for the normal maturation and differentiation of all the various T cell subsets that are described. During fetal and neonatal life, the thymus serves as a micro-environment for the differentiation and expansion of progenitor lymphoid cells that have migrated from the yolk sac, fetal liver, and ultimately the bone marrow. In adults, the thymus continues to play an important role with regard to maintaining immune balance among the various subsets of T cells that are under its control. The first clinical attempts to reconstitute patients with impaired T cell immunity utilized fetal thymus transplants. The chapter discusses the biologic properties attributable to thymic factors in both animals and man. Many of the biologic activities of thymic hormones are mimicked by nonspecific agents, such as endotoxin, prostaglandins, and cyclic adenosine monophosphate. The most important clinical application of the thymic hormones is their potential therapeutic use in selected patients with primary immunodeficiency disorders—for example DiGeorge's syndrome—infections, cancer, and autoimmune disorders.
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